PET is a functional imaging technique in nuclear medicine that produces a three-dimensional image of functional processes in a living object. Typically, a short-lived radioactive isotope tracer, such as fluorodeoxyglucose (FDG), may be injected into the object. The tracer may undergo a positron emission decay (also known as the beta decay) and emit a positron. The positron may annihilate with an electron, generating a pair of annihilation photons (or gamma photons) that move in approximately opposite directions.
A PET system may include a PET detecting module to detect gamma rays. A PET detecting module may include a scintillator array and a plurality of optical channels (e.g., light guides). Each of the plurality of optical channels may guide a light signal to a photosensor. The optical channels may have various configurations. Each of plurality of optical channels may couple to a scintillator. An optical channel may couple to a row (or a column) of scintillators. Generally, with less optical channels, the cost and complexity of the PET system may be lower, but the detection performance of the PET system may be worse. It is desirable to seek a balance between maintaining a good performance and reducing the cost and complexity of the PET system.